Q & A

I just bought a new Saturn that came with daytime running lights. It was one of the safety features that influenced my decision. Now one of my neighbors says they’re a bad idea. What gives?

--S.M., Burbank

Well, like almost anything that has to do with cars and safety, daytime running lights have sparked an argument on both sides. So, herewith, let’s shed some light on this controversy by outlining the arguments for and against.

Those in favor cite the following:

* A cheap way to reduce crashes by making cars more conspicuous and easier to spot from farther away and in low-light situations.

* The Insurance Institute for Highway Safety cites studies in the U.S. , Canada and Scandinavia that show DRLsreduce multiple-vehicle accidents as much as 32%.

* DRLs won’t shorten headlamp bulb life or lower fuel economy.

* The lights won’t create a glare problem, according to a study by the National Highway Transportation Safety Administration, because they are lower in intensity.

Opponents counter with these arguments:

* The advantages in daylight are questionable. If low-light situations call for lights, then require motorists to turn on regular lights earlier.

* They’re annoying and distracting to other drivers.

* Some drivers might think that DRLs are adequate lighting in bad weather.

* More effective in Canada and other northern countries where there are long periods of twilight or overcast skies.

* DRLs are just another way for car makers and light bulb companies to hit the public up for more money.

* Rear center brake lights weren’t as effective as proponents touted, and when all cars have DRLs no vehicle will stand out any more than another.

This last argument is interesting because a study by Transport Canada, which supports the contention that the lights reduce accidents, also found that drivers without the lights run the risk of being masked by those by drivers who do. The study found “that drivers meeting a line of cars in a passing situation were more likely to miss an oncoming car without headlights if it was surrounded by cars that had headlights on.”

This masking effect, which the study attributed to glare or distraction or both, was strongest at dawn and dusk and and worsened quickly as the light level dropped off.

However, the researcher conluded that DRLs increased safety and that motorists without them would do well to add them or use their regular headlights in poor light conditions.

Flag Down Dr. Gear Head

Do you have a question or suggestion for Dr. Gear Head? Write to Dr. Gear Head, Business Section, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053. Or fax us at (213) 237-7837, or e-mail us at highway1@latimes.com.